Seven people have been killed and 14 injured in a bomb blast in China's Xinjiang region.

The explosion happened in Aksu city in the west of the remote western region.

A local government spokeswoman, Hou Hanmin, said a Uighur man drove a three-wheeled vehicle carrying an explosive device into a crowd.

The man was arrested at the scene and investigations were ongoing, Ms Hou said.

Analysis

By Michael BristowBBC News, Beijing

The motive behind what appears to be a bomb blast in China's western Xinjiang region is not yet clear. But many will suspect it is linked to the region's ongoing ethnic tension.

There have not been many major incidents over recent months since last year's riots that left nearly 200 dead. But few people suspect the underlying ethnic problems have been solved.

A visitor to Xinjiang's capital, Urumqi, can instantly see the distrust between these two ethnic groups; they mostly live in separate areas.

Many of Xinjiang's mostly Muslim Uighurs complain that Han Chinese migrants are changing the nature of the region - as well as taking all the best jobs.

Xinjiang's governor, speaking on Thursday before the explosion was known about, was reported to have said that the government faced a long, fierce struggle against separatism.

"It was a three-wheeled vehicle, it has an explosive device on it," she told the BBC Chinese service.

"It exploded while the three-wheeled vehicle ran into the crowd at a street intersection,"

All of the injured were local residents, she said, and four of them had suffered serious injuries.

Last year deadly ethnic riots erupted in Xinjiang after tensions flared between the Muslim Uighur minority and the Han Chinese.

There have also been a number of blasts in Xinjiang in the past, which the government blames on Uighur separatists.

But Uighur activists and human rights groups accuse Beijing of using the issue to crack down on Uighur dissidents, who have complained that waves of Han Chinese migrants have marginalised the Uighur culture.

China has poured troops into Xinjiang, which borders Central Asia, since the unrest in July 2009 in Urumqi which left about 200 people dead.